<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head>
<link rel="STYLESHEET" href="lib.css" type='text/css' />
<link rel="SHORTCUT ICON" href="../icons/pyfav.png" type="image/png" />
<link rel='start' href='../index.html' title='Python documentation Index' />
<link rel="first" href="lib.html" title='Python library Reference' />
<link rel='contents' href='contents.html' title="Contents" />
<link rel='index' href='genindex.html' title='Index' />
<link rel='last' href='about.html' title='About this document...' />
<link rel='help' href='about.html' title='About this document...' />
<link rel="next" href="expat-errors.html" />
<link rel="prev" href="expat-example.html" />
<link rel="parent" href="module-xml.parsers.expat.html" />
<link rel="next" href="expat-errors.html" />
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<meta name='aesop' content='information' />
<title>8.5.4 Content Model Descriptions </title>
</head>
<body>
<div class="navigation">
<div id='top-navigation-panel' xml:id='top-navigation-panel'>
<table align="center" width="100%" cellpadding="0" cellspacing="2">
<tr>
<td class='online-navigation'><a rel="prev" title="8.5.3 Example"
  href="expat-example.html"><img src='../icons/previous.png'
  border='0' height='32'  alt='Previous Page' width='32' /></a></td>
<td class='online-navigation'><a rel="parent" title="8.5 xml.parsers.expat  "
  href="module-xml.parsers.expat.html"><img src='../icons/up.png'
  border='0' height='32'  alt='Up one Level' width='32' /></a></td>
<td class='online-navigation'><a rel="next" title="8.5.5 expat error constants"
  href="expat-errors.html"><img src='../icons/next.png'
  border='0' height='32'  alt='Next Page' width='32' /></a></td>
<td align="center" width="100%">Python Library Reference</td>
<td class='online-navigation'><a rel="contents" title="Table of Contents"
  href="contents.html"><img src='../icons/contents.png'
  border='0' height='32'  alt='Contents' width='32' /></a></td>
<td class='online-navigation'><a href="modindex.html" title="Module Index"><img src='../icons/modules.png'
  border='0' height='32'  alt='Module Index' width='32' /></a></td>
<td class='online-navigation'><a rel="index" title="Index"
  href="genindex.html"><img src='../icons/index.png'
  border='0' height='32'  alt='Index' width='32' /></a></td>
</tr></table>
<div class='online-navigation'>
<b class="navlabel">Previous:</b>
<a class="sectref" rel="prev" href="expat-example.html">8.5.3 Example</a>
<b class="navlabel">Up:</b>
<a class="sectref" rel="parent" href="module-xml.parsers.expat.html">8.5 xml.parsers.expat  </a>
<b class="navlabel">Next:</b>
<a class="sectref" rel="next" href="expat-errors.html">8.5.5 Expat error constants</a>
</div>
<hr /></div>
</div>
<!--End of Navigation Panel-->

<h2><a name="SECTION0010540000000000000000"></a><a name="expat-content-models"></a>
<br>
8.5.4 Content Model Descriptions 
</h2>

<p>
Content modules are described using nested tuples.  Each tuple
contains four values: the type, the quantifier, the name, and a tuple
of children.  Children are simply additional content module
descriptions.

<p>
The values of the first two fields are constants defined in the
<code>model</code> object of the <tt class="module">xml.parsers.expat</tt> module.  These
constants can be collected in two groups: the model type group and the
quantifier group.

<p>
The constants in the model type group are:

<p>
<dl><dt><b><tt>XML_CTYPE_ANY</tt></b></dt>
<dd>
The element named by the model name was declared to have a content
model of <code>ANY</code>.
</dd></dl>

<p>
<dl><dt><b><tt>XML_CTYPE_CHOICE</tt></b></dt>
<dd>
The named element allows a choice from a number of options; this is
used for content models such as <code>(A | B | C)</code>.
</dd></dl>

<p>
<dl><dt><b><tt>XML_CTYPE_EMPTY</tt></b></dt>
<dd>
Elements which are declared to be <code>EMPTY</code> have this model type.
</dd></dl>

<p>
<dl><dt><b><tt>XML_CTYPE_MIXED</tt></b></dt>
<dd>
</dd></dl>

<p>
<dl><dt><b><tt>XML_CTYPE_NAME</tt></b></dt>
<dd>
</dd></dl>

<p>
<dl><dt><b><tt>XML_CTYPE_SEQ</tt></b></dt>
<dd>
Models which represent a series of models which follow one after the
other are indicated with this model type.  This is used for models
such as <code>(A, B, C)</code>.
</dd></dl>

<p>
The constants in the quantifier group are:

<p>
<dl><dt><b><tt>XML_CQUANT_NONE</tt></b></dt>
<dd>
No modifier is given, so it can appear exactly once, as for <code>A</code>.
</dd></dl>

<p>
<dl><dt><b><tt>XML_CQUANT_OPT</tt></b></dt>
<dd>
The model is optional: it can appear once or not at all, as for
<code>A?</code>.
</dd></dl>

<p>
<dl><dt><b><tt>XML_CQUANT_PLUS</tt></b></dt>
<dd>
The model must occur one or more times (like <code>A+</code>).
</dd></dl>

<p>
<dl><dt><b><tt>XML_CQUANT_REP</tt></b></dt>
<dd>
The model must occur zero or more times, as for <code>A*</code>.
</dd></dl>

<p>

<div class="navigation">
<div class='online-navigation'>
<p></p><hr />
<table align="center" width="100%" cellpadding="0" cellspacing="2">
<tr>
<td class='online-navigation'><a rel="prev" title="8.5.3 Example"
  href="expat-example.html"><img src='../icons/previous.png'
  border='0' height='32'  alt='Previous Page' width='32' /></a></td>
<td class='online-navigation'><a rel="parent" title="8.5 xml.parsers.expat  "
  href="module-xml.parsers.expat.html"><img src='../icons/up.png'
  border='0' height='32'  alt='Up one Level' width='32' /></a></td>
<td class='online-navigation'><a rel="next" title="8.5.5 expat error constants"
  href="expat-errors.html"><img src='../icons/next.png'
  border='0' height='32'  alt='Next Page' width='32' /></a></td>
<td align="center" width="100%">Python Library Reference</td>
<td class='online-navigation'><a rel="contents" title="Table of Contents"
  href="contents.html"><img src='../icons/contents.png'
  border='0' height='32'  alt='Contents' width='32' /></a></td>
<td class='online-navigation'><a href="modindex.html" title="Module Index"><img src='../icons/modules.png'
  border='0' height='32'  alt='Module Index' width='32' /></a></td>
<td class='online-navigation'><a rel="index" title="Index"
  href="genindex.html"><img src='../icons/index.png'
  border='0' height='32'  alt='Index' width='32' /></a></td>
</tr></table>
<div class='online-navigation'>
<b class="navlabel">Previous:</b>
<a class="sectref" rel="prev" href="expat-example.html">8.5.3 Example</a>
<b class="navlabel">Up:</b>
<a class="sectref" rel="parent" href="module-xml.parsers.expat.html">8.5 xml.parsers.expat  </a>
<b class="navlabel">Next:</b>
<a class="sectref" rel="next" href="expat-errors.html">8.5.5 Expat error constants</a>
</div>
</div>
<hr />
<span class="release-info">Release 2.5.1, documentation updated on 18th April, 2007.</span>
</div>
<!--End of Navigation Panel-->
<address>
See <i><a href="about.html">About this document...</a></i> for information on suggesting changes.
</address>
</body>
</html>
